Clockwork-operated detonators



Feb. 9, 1960 e. SCHMIDT I CLOCKWORK-OPERATED DETONATORS 3 Sheets-Sheet 1 Filed April 4, 1958 r Z WW Z J W K [M M/ 4% Feb. 9, 1960 e. SCHMlDT CLOCKWORK-OPERATED DETONATORS 3 Sheets-Sheet 2 Filed April 4, 1958 Inventor? f I; w 4 in! I Filed April 4, 1958 Feb. 9, 1960 SCHMIDT 2,924,721

CLOCKWORK-OPERATED DETONATORS 3 Sheets-Sheet 3 fay 7 United States Patent CLOCKWORK-OPERATED DETONATORS Gerhard Schmidt, .Krefeld-Uerdingen, Germany, assignor to Firma Wasag Chemie Aktiengesellschaft, Essen, Germany Application April-'4, 1958, Serial No. 726,577 .Claims priority, application Germany April 4, 1957 12 Claims. -(Cl. 290-1) The present invention relates to apparatus for firing explosive. charges, and moreparticularly to an improved rough handlingand are often carried from one to another location. It is thereforeimportant that a detonator be constructed as a lightweight, .compact, sturdy and conveniently transportable device, but such requirements are not fully met ,by available apparatus of this general character. For example,'in prior detonators the drive means which rotates the current generator is arrested only indirectly by being rigidly connected with a gear performing no other'function but to mesh with an arresting apparatus to thus prevent undesired rotation of the generators armature. Such construction adds to the overall weight, height and to number of component parts. In addition, due to relative complicatedness of the clockwork-arresting and current-generating mechanisms, the prior. apparatus require frequent repairs and do not allow for convenient access to all component parts without at least partial dismantling.

Accordingly, it is an important object of the present invention to provide an improved clockwork-operated detonator which is sturdy, of lightweight construction and considerably simpler than the prior devices used for the same general purpose.

Another object of the invention is to provide an electric detonator with a greatly reduced number of component parts.

A further object of the invention is to provide a device of the above described character which is so constructed that the drive means rotatable by the unwinding clockwork mechanism is positively arrested in a fully automatic manner at all times save when the firing of a charge connected to the detonator is desired.

The above and many other objects of the invention are attained by the provision of a clockwork-operated detonating apparatus wherein the driving means which is rotated by the mainspring and in turn drives the armature of the current generating means is directly and automatically arrested while the clockwork mechanism is wound. Thus, in contrast to the aforementioned detonators of known construction, the novel device provides for direct blocking of driving means in that an arresting device is movable into direct contact with the teeth of the main pinion which latter is driven by the mainspring and in turn drives the shaft on which the generators armature is mounted. The arresting device may be formed as a toothed bar or, if desired, may be provided with internal gearing. It is preferred to employ an involute tooth system on the arresting device to insure simultaneous mesh between more than a single pair of teeth.

According to another feature of the instant invention which may be applied with great advantage in the improved detonator as well as. in prior apparatus of somewhat similar construction, the contactor mechanism and the arresting device for the generator drive-are controlled by asingle element. The control element is preferably an annular body mounted concentrically with and for rotation about the field of the current generator. This also contributes to greater simplicity of .and easier access to all parts of the improved detonator, especially since the connection of said control element withthe contacting mechanism on the one hand, and with the arresting de vice on the other hand, too, is extremely simple and consists of a greatly reduced number of component'parts. This allows for construction of a very compact, lightweight system with less likelihood of malfunction or breakdown, as well as in greatly increased reliability .and extended useful life of the improved detonator.

It is desirable to shape the annular control element as a ring gear which is directly coupled with the winding shaft of the clockwork mechanism and which, in addition, carries at least one part of the contactor mechanism, preferably the contact segment which is an element well known and often employed in devices of this general character.

The arresting device itself may be locked in arresting or non-arresting position by a specially designed locking member which has limited freedom of rotational movement when engaged by the ring gear. This locking member, which is constantly urged into locking position by ,a resilient element, is provided with several arms one of which carries a cam so mounted as to selectively block movements of arresting device from or into arresting position depending upon whether the clockwork, mechanism is being wound or drives the current generator when the detonation of a distant charge is desired. Other arms of the locking member are so disposed that the ring gear may engage same at certain stages of its rotation and to thus displace the locking device with a view to either allow return of arresting device into arresting position, i.e. into mesh with the main pinion of the generator drive, or away from the latter to allow rotation of the generators armature when the explosive charge is about to be fired.

Thus, it will be seen that the control ofcurrent generators drive in my improved detonator is achieved merely 'by a ring gear, a locking member and an arresting device, i.e. an assembly comprising a very small number of parts. The entire detonator, in fact, consists only of -a very simple clockwork mechanism including a winding shaft and a mainspring, a current generator, a drive for I the generator directly rotated by the winding shaft, a

ring gear, an arresting device for the generators drive, locking means for the arresting device coupled with'the ring gear, and the contactor mechanism.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of a specific embodiment when read in connection with the accompanying drawings, in which:

Fig. 1 is a vertical section through theimproved detonator taken on line Il of Fig. 2 as seen in the direction of arrows;

Fig. 2 is an enlarged top plan view of the generator drive, of arresting mechanism therefor and of locking means for the arresting mechanism, as seen from line l1ll in Fig. 1 in the direction of arrows; and

Fig. 3 is an enlarged section taken on line III-III of Fig. 1.

Referring first to Fig. 1, the improved apparatus comprises a housing consisting of a lower section 1 which may be of elliptical shape as best seen in Figs. 2 and 3, an upper section 2, and a. cover member 3. Cover member 3 is rigidly connected to housing section 2 by screw 3 bolts 11. The blasting current generated in the detonator is led to two terminals 4 one of which is illustrated in Fig. 1 as attached to housing section 2. The

mainspring 7 is wound by a shaft 5 whose upper end 5a, projecting from a recess 3a in cover member 3, is

ofnon-circular contour to facilitate attachment thereto of a suitable tool (not shown). A nut 6, fixed to shaft 5, is connected with one end of mainspring 7 which latter is installed in a casing 8. The other end of element 7 extends through a slot 8a in casing 8 and is secured to a retaining member 10 located in a recess 9 of the upper housing section 2.

A ratchet 12 is rigidly connected to shaft 5; its teeth are in mesh with a pawl 13 which latter is constantly urged into the position shown in Fig. 2 by a leaf spring 33. Pawl 13 is pivotally fixed to the driving pinion 14 which thus rotates in unison with the ratchet when the assembly of members 5 and 12 is rotated in anti-clockwise direction by the mainspring 7, reference being had to Fig. 2. In accordance with one feature of the present invention, pinion 14 is automatically and directly arrested not only while the mainspring 7 is wound but at all times excepting when the firing of an explosive charge whose leads are connected to terminals 4' is initiated by rotation of shaft 19, as will be described in more detail hereinafter.

Rotation of pinion 14 is blocked by an arresting member 15 which latter, as shown in Fig. 2, may assume the form of a toothed bar whose end facing the peripheral zone of pinion 14 is provided with an involute tooth system 16 to mesh with teeth 14a of the pinion. For initiating the firing of an explosive charge (not shown) whose conductors of leads are connected to terminals 4, and assuming that the mainspring 7 is under tension, shaft 19 is rotated in anticlockwise direction whereby a forked lever 18, rigidly fixed to shaft 19, engages and entrains a lug 17 integral .with arresting member 15 to move said arresting member out of mesh with the teeth 14a of pinion 14, i.e. in the direction of arrow 20. The pinion is now free to rotate under the influence of uncoiling mainspring 7 which turns shaft 5 and ratchet 12 in anticlockwise direction. Shaft 19 has an upper end 19a of a non-circular contour extending into a recess 3b in the cover member 3 to be rotated by a suitable tool when the firing of explosive charge is desired. As shown in Fig. 1, the non-circular ends 5a and 19a of shafts 5 and 19, respectively, are similar to be operatable by a single tool.

Teeth 14a of pinion 14 also mesh with the teeth of a sprocket 21 which is rigidly mounted on the shaft 22a of generators armature 22. This armature is disposed in a field 23' and between pole shoes 24, 25; its shaft 22a rotates in bearings 26, 27 located in bearing plates 28, 29, respectively. Plate 28 is fixed to housing section 2 by a number of threaded bolts 28a. Current is collected from collector member 30 by a pair of brushes 31, 32. Collector 30 is mounted on the shaft 22a. In the embodiment shown element 22 is a so-called drum armature.

The peripheral zone at the lower end of shaft 5 in housing section 1 is provided with external teeth, as at 34, to mesh with the teeth of a ring gear 35. Thus, shaft 5 and ring gear are directly and positively coupled. Member 35 concentrically surrounds the field 23 and is mounted for rotation about a reduced zone 23a of the latter. Its function is to control the arresting member 15 and the contactor mechanism and it thus actually serves as a sole control element for proper operation of my improved detonator.

Contactor mechanism 37 comprises a segmental contact 36 which is mounted on but insulated from'ring gear 35, and contact bolts 38, 39 and 40 which are carried by the field 23. Blasting current is led from bolts 38- 40 to terminals 4 in well known manner over segment 36; therefore, the details of this electrical connection were omitted in the drawing as they form no part of the present invention.

As shown in Fig. 3, ring 35 carries a connecting assembly consisting of bracket 42, spring 41 and a catch 43. Spring 41 constantly urges member 43 to pivot in its bracket 42 in such direction that its projecting nose 43a extends into a recess 44 provided in the arm 45 of a locking member 48. The latter is of generally discoid shape and, in addition to arm 45, comprises a second arm 49 which is in the path of a projecting pin 58 carried by ring gear 35, and a third arm 48a which terminates in a cam 46 whose function is to block the arresting member 15. A coil spring 47 constantly urges locking member 48 into idle position.

Arresting member 15, as shown in Fig. 2, has a laterally extending arm 15a which carries a pin 15b. This pin is so located as to be blocked by cam 46 in either of two directions depending on the position of arresting member 15. If the teeth 16 of member 15 are in mesh with teeth 14a of pinion 14, cam 46 may be brought into position behind the pin 15b to thus block the movements of arresting member 15 in the direction of arrow 20, i.e. out of mesh with pinion 14. If, however, the arresting member 15 is in its position 15' shown in Fig. 2 in phantom lines, i.e. when the pinion is free to rotate, and the pin 15b is in its phantom-line position 15b, the cam 46 blocks return movements of member 15 into arresting or blocking position with respect to pinion 14. The movements of arresting member 15 radially of pinion 1 4 in, and opposed to, the direction of arrow 20 are guided by a pair of lugs 28a, 28b, which are fixed to the upper face of bearing plate 28 and are received in respective closed slots 15c, 15d provided in arresting member 15. The latter is constantly urged into arresting position by a leaf spring 52 which'is also mounted on hearing plate 28 and bears against a stud 15a on the arresting member.

The improved mechanism of the detonator operates as follows:

When the mainspring 7 is wound by rotating shaft 5 in clockwise direction (see Fig. 2), the teeth 34 of shaft 5 mesh with the teeth of ring gear 35 and entrain the latter in anticlockwise direction (see Fig. 3). Arresting member 15 is in the position of Fig. 2 and thus pawl 13 merely rides over the teeth of ratchet 12. In the first stage of its rotation about field 23, ring gear 35 entrains the locking member 48 by means of catch 43 whose nose 43a extends into the recess 44 of arm 45. Member 48 thus rotates with gear 35 and its cam '46 moves away and out of blocking position with respect to the pin 15b of arresting member 15. Member 15 thus returns into mesh with pinion 14 under the influence of spring 52. A stud 5'1 fixed to hearing plate 28 is in the path of an extension or cam 43b on member 43 and thus pivots member 43 away from locking element 48 whereby the nose 43a releases arm .45 to permit return of member 48 under the influence of coil spring 47. Cam 46 is now again in blocking position with respect to the pin 15b of arresting member 15; the latter is thus prevented from moving in the direction of arrow 20.

Shortly before the winding of mainspring 7 is com pleted, member 50 traveling with ring gear 35 entrains the arm 49 of locking member 48 and, by thus displacing disc 48, again moves cam 46 out of blocking position with respect to the pin 15b of arresting member 15. The latter is now free to be moved in the direction of arrow 20 by means of forked lever 18 and shaft 19 when the latters end 19a is rotated. 7

During the winding of mainspring 7, segment 36 slides along bolts 3'8-40 of contactor mechanism 37 without any effect since the armature 22 and its sprocket 21 are blocked by pinion 14 which is held in arrested position by member 15.

The unwinding of mainspring 7 after the arresting member 15 releases pinion .14 upon rotation of shaft 19 and forked, lever 18 causes a sequence of movements generally'reverse of 'that'just' described.

Shaft is rotated by the unwinding mainspring 7 and its toothed end 34: entrains ring Wheel 35 for rotation in clockwise direction (see Fig. 3). Stud 50 thus moves away from the arm 49 of discoid member 48 and permits the latter to return with its cam 46 into blocking position under the influence of spring 47. Since the arresting member is now in position 15, i.e. it does not block the rotation of pinion 14, cam 46 prevents return movements of pin 15b from its position 15b under the influence of leaf spring 52, and thus positively prevents member 15 from arresting the rotation of pinion 14. The latter is rotated by mainspring 7 over shaft '5, ratchet '12 and pawl 13 in anticlockwise direction.

Shortly before the mainspring 7 is fully unwound, projection 43a of catch 43 again engages the arm 45 of member 48 and thus moves cam 46 out of blocking position. The arresting member 15 and itspin 1511 are now free to return into their full-line position (Fig. 2) under the influence of spring 5'2 and to again block the rotation of'pinion 1'4.

While the mainspring 7 unwinds, pinion 14 drives sprocket 21 and armature 2.2. When the generated current has reached its maximum strength, segment 36 traveling with ring gear 35 slides along contact bolts 3840 to supply a series of electric impulses to terminals 4 and to thusinitiate the detonation of a charge electrically connected thereto.

It will be understood that certain elements described above, or two or more together, may also find useful application-in other types of detonators differing from the type'described above.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by-applying current knowledge readily adapt it for various' applications without omitting features that, from the standpointof prior'art, fairly constitute essential characteristics of the generic or specific aspects of thisinvention and, therefore, such' adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired Letters Patent is:

1. An apparatus for firingexplosive charges comprising, in combination, a clockwork mechanism including a winding shaft and a mainspring arranged to be wound by saidshaft and to rotate. said shaft during unwinding; generator means including a rotatable armature for supplying a series of electric impulses; an operative connection between said shaft and said armature including a pinion so fixed to said shaft that said shaft and said pinion rotate inunison when, said mainspring unwinds whereby to rotate said armature; and arresting means for blocking the rotation of said pinion when said mainspring is wound by said shaft, said arresting means including a toothed element movable into and away from mesh with the teeth of said pinion.

2. An apparatus for firing explosive charges comprising, in combination, a clockwork mechanism includinga winding shaft and a mainspring arranged to be wound by said shaft and to rotate said shaft during unwinding; generator means including a rotatable armature for supplying a series of electric impulses; an operative connection between said shaft and said armature including a pinion so fixed to said shaft that said shaft and said pinion rotate in unison when said mainspring unwinds whereby to rotate said armature; and arresting means for blocking the rotation of said pinion when said mainspring is wound by said shaft, said arresting means including a toothed bar movable radially into and away from mesh with the teeth of said pinion.

3. An apparatus for firing explosive charges comprising, in combination, a clockwise mechanism including a shaft and a mainspring arranged to be wound by said shaft and to rotate said shaft during unwinding; generator to be secured by means including a rotatable armature for supplying a series of electric impulses; terminal means electrically connectable with said generator means; an operative connection between said shaft and said armature including a pinion so fixed to said shaft that'said shaft and said pinion rotate in unison when said mainspring unwinds whereby to rotate said armature; and arresting means for blocking the rotation of 'said pinion when said mainspring is wound on said shaft, said last mentioned means including an internally toothed element movable into and away from mesh with the teeth of said pinion.

4. An electric detonator comprising, in combination, a clockwork mechanism including a shaft and a mainspring arranged to be wound by said shaft and to rotate said shaft during unwinding; generator means including a rotatable armature for supplying'a series of electric impulses; terminal means; an electrical connection between said terminal means and said generator means including first contact means electrically connected with said generator means and second contact means electrically connectable with said terminal means, said second contact means being movable intoand out of contact with said first contact means; an operative connection between said shaft and said armature including a pinion so connected with said shaft that said pinion and said shaft are driven in unison when said mainspring unwinds whereby to rotate said armature; arresting means for blocking the rotation of saidpinion when said mainspring is wound by said shaft and arranged to be moved into and'away from biocking position with respect to said pinion; and a control element operatively connected with said shaft and with said arresting means for selectively maintaining said arresting means in blocking and releasing position, respectively, with respect to said pinion, said control element being further operatively connected with said secondcontact means for moving same into contact with said first contact means when said mainspring unwinds.

5. An electric detonator comprising, in combination, a clockwork mechanism including a shaft and a mainspring arranged to be wound by said shaftand to rotate said shaft during unwinding; generator means including a rotatable armature for supplying a series of electric impulses; terminal means; an electrical connection between said terminal means and said generator means including first contact means electrically connected with said generator means and second contact means electrically connectable with said terminal means, said second contact means being movable into and out of contact with said first contact means; an operative connection between said shaft and said armature including a pinion so connected with said shaft that said pinion and saidshaft are driven inunison when said mainspring'unwinds whereby to rotate said armature; a toothed bar for blocking the rotation of'said pinion when said mainspring is wound by said shaft and arranged to be moved radially into and away from mesh with the teeth of said pinion; and a control element operatively connected with said shaft and with said bar for selectively maintaining said bar in mesh and out of mesh, respectively, with respect to the teeth of said pinion; and an operative connection between said controlelement and said second contact means for moving same into contact with said first contact means when said mainspring unwinds and said control element is actuated by said shaft.

6. An electric detonatorcomprising, in combination, a clockwork mechanism including a shaft and a mainspring arranged to bewound by said shaft and to rotate said shaft during unwinding; generator means for supplying a series of electrical impulses, said generator means including a cylindrical field and an armature rotatably received in said field; a drive connection between said shaft and said armature including a pinion so connected with said shaft that said pinion and said shaft are driven in unison when said mainspring unwinds whereby to rotate said armature; arresting means having a first position for 7 blocking the rotation of said pinion when said mainspring is wound and asecond position in which said pinion is free to rotate when said mainspring unwinds; r'esilien't means for constantly, urging said arresting means into said first position; releasing means for moving said arresting means into said second position whereby said mainspring is free to unwind; anannular element rotatably mounted about said field and operatively connected with said shaft for rotation therewith; first contact means electrically connected with said generator means for receiving impulses therefrom; second contact means attached to said annular element and movable into contact with said first'contact means when said annular element rotates; terminal means electrically connected with said second contact means; and means actuatable by said annular element for locking said arresting means in said first position when said annular element is rotated in one direction by said shaft during winding of said mainspring,

and for locking said arresting means in said second position when said 'releasingmeans is actuated and said coil spring unwinds.

7. An electric detonator comprising, in combination, a clockwork mechanism including a shaft'and a mainspring arranged to be wound by said shaft and to rotate said shaft during unwinding; generator means for supplying a series of electrical impulses, said generator means including a cylindrical field and an armature rotatably received in said field; a drive connection between said shaft and said armature including a pinion so connected with said shaft that said pinion and said shaft are driven in unison when said mainspring unwinds; a gear meshing with said pinion and rigidly connected with said armature for rotating same when said mainspring unwinds; arresting means mounted for movement with a first position in which the rotation of said pinion is blocked and into a second position in which said pinion is free to rotate; resilient means for constantly urging said arresting means into said first position; releasing means for moving said arresting means into said second position whereby said mainspringis free to unwind and to rotate said armature; a ring gear rotatably mounted about said field and directly coupled with 'said shaft for rotation therewith in two directions; first contact means electrically connected with said generator means; second contact means attached to said ring gear and movable into contact with said first contact means when said ring gear is driven by said shaft; terminal means electrically connected with said second contact means; and locking means for maintaining said arresting means in said first position when said mainspring is wound and, in said second position when said releasing means is actuated, said last mentioned means including a cam, means for constantly urging said cam into a position of rest in which said cam blocks the movements of said arresting means, and an operative connection betweensaid ring gear and said locking means for temporarily displacing said cam from said position of rest when said ring gear is driven in either direction.

8. An electric detonator comprising, in combination, a clockwork mechanism including a shaft and a mainspring arranged to be wound by said shaft and to rotate said shaft during unwinding; generator means for supplying a series of electrical impulses, said generator means including a cylindrical field and an armature rotatably received in said field; a drive connection between said shaft and said armature including a pinion so connected with said shaftthat said pinion and said shaft are driven in unison when said mainspring unwinds whereby to rotate said armature; arresting means having a first position for blocking the rotationof said pinion when said mainspring is wound and a second position in which said pinion is free torotate when said mainspring unwinds; resilient means for constantly urging said arresting means into'said first position; releasing means for moving said arresting means into said second position wherebysaid mainspring is free to unwind; an annular element rotatably mounted about said field and operatively connected with said shaft for rotation there with; contact means electrically connected with said generator means for receiving impulses therefrom; a segmental contactor attached to said annular, element and movable into contact with said contact means when said annular element rotates; terminal means electrically connected with said contactor; and means actuatable by said annular element for locking said arresting means in said first position when said annular element is totated in one direction by said shaft during winding of said mainspring, and for locking said arresting means in said second position when said releasing means is actuated and said coil spring unwinds.

9. An electric detonator comprising, in combination, a clockwork mechanism including a shaft and a mainspring arranged to be wound by said shaft and to rotate said shaft during unwinding; generator means for supplying a series of electrical impulses, said generator means including a cylindrical field and an armature rotatably received in said field; a drive connection between said shaft and said armature including a pinion so connected with said shaft that said pinion and said shaft aredriven in unison when said mainspring unwinds; a gear meshing with said pinion and rigidly connected with said armature for rotating same when said mainspring unwinds; arresting means mounted for movements into a first position in which the rotation of said pinion is blocked and into a second position in which said pinion is free to rotate; resilient means for constantly urging said arresting means into said first position; releasing means for moving said arresting means into said second position whereby said mainspring is free to unwind and to rotate said armature; a ring gear rotatably mounted about said field and directly coupled with said shaft for rotation therewith in two directions; contact means electrically connected with said generator means; a segmentshaped contactor attached to said ring gear and movable into sliding contact with said contact means when said ring gear is driven by said shaft; terminal means electrically connected with said contactor; and locking means for maintaining said arresting means in said first position when said mainspring is wound and in said second position when said releasing means is actuated, said last mentioned means including a cam, means for constantly urging said cam into a position of rest in which said cam'blocks the movements of said arresting means, and an operative connection between said ring gear and said locking means for temporarily displacing said cam from said position of rest when said ring gear is driven in either direction.

10. An electric detonator comprising, in combination, a clockwork mechanism including a shaft having a toothed portion and a mainspring so connected with said shaft as to be wound when the latter is rotated in one direction and to rotate said shaft in the other direction during unwinding; generator means for supplying a series of electrical impulses, said generator means including a cylindrical field and an armature rotatably received in said field; a drive connection between said shaft and said armature including a pinion so connected with said shaft as to rotate in unison therewith when said mainspring unwinds; a gear meshing with said pinion and rigidly connected with said armature for rotating the latter when said mainspring unwinds; arresting means mounted for movements radially of said pinion into a first position of mesh with the teeth of said pinion and into a second position away from said pinion; resilient means for constantly urging said arresting means into said first position; releasing means for moving said arresting means into said second position whereby said mainspring is free to unwind and said armature is rotated; 21 ring gear rotatably mounted about said field and meshing with the toothed portion of said shaft; first contact means electrically connected with said generator means; second contact means attached to said ring gear and movable into sliding contact with said first contact means; terminal means electrically connected with said contact means when said ring gear is rotated; and a discoid member coaxial with and angularly displaceable by said ring gear for a predetermined distance when said ring gear is moved in either direction, said discoid member having a position of rest and including cam means for blocking the movements of said arresting means when said discoid member is in said position of rest and movable away from said arresting means when said discoid member is displaced; and resilient means for constantly urging said discoid member into said position of rest.

11. An electric detonator comprising, in combination, a clockwork mechanism including a first shaft having a toothed portion, and a mainspring so connected with said shaft as to be wound when said shaft is rotated in one direction and to rotate said shaft in the other direction during unwinding; a pinion mounted on said shaft; means for connecting said shaft with said pinion in such a way that said pinion and said shaft rotate in unison when said mainspring unwinds; a second shaft parallel with said first shaft; a gear rigidly fixed to said second shaft and meshing with said pinion; an armature fixed to said second shaft; a stationary field disposed about said armature; a ring gear rotatably mounted on said field and meshing with the toothed portion of said first shaft; stationary contactors electrically connected with said armature and attached to said field; a moving contactor attached to said ring gear and slidably engaging selected ones of said stationary contactors when said ring gear is driven by said first shaft; a pair of terminals electrically connected with said stationary contactors for receiving a series of impulses when said armature is rotated while said mainspring unwinds; a toothed bar having a pin and mounted for sliding movements radially of said pinion; first resilient means for constantly urging said bar into mesh with said pinion; mainspring releasing means operatively connected with said bar for moving same away from said pinion; a rotatably mounted discoid member having a first arm, a second arm and a cam; second resilient means for constantly urging said discoid member into a first position in which said cam is in the path of said pin whereby said bar is locked in the position of mesh or in the position away from said pinion; connecting means carried by said ring gear for releasably coupling said first arm with said ring gear when said first shaft is rotated to wind said mainspring whereby said discoid member is moved into a second position in which said cam is out of the path of said pin and said first resilient means returns said bar into mesh with said pinion; means in the path of said connecting means for disconnecting same from said discoid member after a short angular displacement of said ring gear whereby said second resilient means returns said discoid member into a position in which said cam is in the path of said pin; and a projection attached to said ring gear arranged to engage with said second arm shortly before said first shaft completes the winding of said mainspring to displace said discoid member into a position in which said cam is out of the path of said pin whereby said bar may be moved away from said pinion by said releasing means.

12. An electric detonator comprising, in combination, a housing having a cover; a clockwork mechanism in said housing including a first shaft having an upper end of non-circular contour extending from said cover and a toothed lower end, and a mainspring so connected with said shaft as to be wound when said shaft is rotated in one direction and to rotate said shaft in the other direction during unwinding; a ratchet coaxially fixed to an intermediate portion of said shaft; a pinion coaxial with said shaft; a pawl fixed to said pinion and engaging with said ratchet when said shaft is driven while said mainspring unwinds; a second shaft in said housing; gear means fixed to said second shaft and meshing with said pinion; an armature fixed to said second shaft; a field mounted in said housing and surrounding said armature; contact means attached to said field and electrically connected with said armature; a ring gear concentrically surrounding said field and meshing with the lower end of said first shaft; a contact element fixed to said ring gear and movable into sliding contact with said contact means when said ring gear is rotated by said first shaft; terminals extending from said housing and electrically connected with said contact means by said contact element when said ring gear and said armature are rotated in response to unwinding of said mainspring to receive a series of impulses; a supporting plate fixed to said housing; toothed arresting means fixed to said plate for sliding movement radially of said pinion and having a first pin and a second pin; a third shaft having an upper end of non-circular contour extending from said cover, and a lower end adjacent to said first pin; a forked lever fixed to the lower end of said third shaft and engaging said first pin in such a way as to move said arresting means away from said pinion when said third shaft is rotated in one direction; first resilient means for constantly urging said arresting means into mesh with said pinion; a locking member rotatably mounted on said plate and having a first arm defining a recess, a second arm, and a cam; second resilient means for constantly urging said locking member into a position in which said cam is in the path of said second pin to prevent movements of said arresting means with respect to said pinion; a connection between said ring gear and said first arm including a catch pivotally fixed to said ring gear and having a projection extendable into said recess, and third resilient means for constantly urging said catch into engagement with said first arm, said catch being so disposed as to engage with said first arm when said mainspring is fully unwound; a member fixed to said plate in the path of said catch for disconnecting the latter from said first arm after short angular movements of said ring gear in response to winding of said mainspring; and an element fixed to said ring gear and engageable with said second arm shortly before the winding of said mainspring is completed.

References Cited in the file of this patent UNITED STATES PATENTS 1,072,511 Schafiler Sept. 9, 1913 1,363,585 Haddow Dec. 28, 1920 1,479,152 Myers Jan. 1, 1924 1,788,892 Schaffler Jan. 13, 1931 2,192,542 Benedetti Mar. 5, 1940 2,524,005 Boe Sept. 26, 1950 

